<Canvas  
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    x:Class="Thumb_wcp.Pane1"
>
  <!--<Snippet1>-->
  <Canvas Width="100" Height="100" Background="Green" Name="myCanvasStretch">
    <TextBox Canvas.Left="0"  Canvas.Top="0"  Name="changes" 
         Width="{Binding ElementName=myCanvasStretch,Path=Width}"  
         Height="{Binding ElementName=myCanvasStretch,Path=Height}" 
         Text="Size: 100, 100" Background="Green" Foreground="Yellow"
         BorderThickness="0"/>

    <!--<SnippetThumb>-->
    <Thumb Name="myThumb" Canvas.Left="80" Canvas.Top="80" Background="Blue" 
          Width="20" Height="20" DragDelta="onDragDelta" 
          DragStarted="onDragStarted" DragCompleted="onDragCompleted"
          />
    <!--</SnippetThumb>-->

  </Canvas>
  <!--</Snippet1>-->
</Canvas>
